\documentclass{article}

\usepackage{pgfplots}

\pgfplotsset{compat=1.14}

\begin{document}

\begin{tikzpicture}
%\tracingcommands=2\tracingmacros=2
	\begin{axis}[trig format plots=rad, z buffer=sort,
		colormap={CM}{
			of colormap={viridis,
				target pos={-1,-0.8,-0.6,-0.5,-0.2,0},
				source pos={0,250,500,750,1000,1000},
			}
		},
		colormap access=const,
		colormap access/extra interval width=0,
		view={90}{0},
		grid=major,
		colorbar,
	]
	\addplot3[surf,shader=interp,samples=5,domain=0:2*pi,y domain=-1:0] ({y*cos(x)},{y*sin(x)},y);
	\end{axis}
\end{tikzpicture}
\end{document}

